1. Technical Field
The present invention relates to personal computers and other portable information processing devices provided with functionality for receiving digital television broadcasts.
2. Description of Related Art
In recent years personal computers (PCs) outfitted with television-broadcast receiving functionality have begun to gain popularity. At present equipping desktop personal computers with television functionality has become common, but when digital terrestrial TV broadcasting is launched in 2003 (in Japan), equipping mobile terminals such as notebook PCs with television functionality in order to be able to view a relatively high-quality TV picture while on the go is anticipated.
In digital terrestrial TV broadcasting, a single channel is apportioned into thirteen segments, and by combining these segments, program-multiplexing a maximum of three programs is possible. Various services, such as for example simultaneously broadcasting three programs whose image quality (resolution) corresponds to SDTV (Standard Definition TV) programs, or broadcasting only a single program whose image quality corresponds to HDTV (High Definition TV) programs, are scheduled to be implemented.
An example of television functionality installed in a notebook PC is illustrated in FIG. 7.
Herein, notebook PC 100 is equipped with, among other components, an antenna 110 for receiving data signals from digital terrestrial TV broadcasting, a TV reception module 120, a signal-processing unit 130 that restitutes received data signals into image data, and a display unit 140 for displaying the image data.
TV reception module 120 includes a tuning unit 121, and a baseband processing unit 122 that demodulates the received signals and converts them into MPEG data. Likewise, the signal-processing unit 130 is equipped with an MPEG decoding unit 131 for decoding into image data MPEG data sent out from the TV reception module 120.
In order to perform ordinary PC functions, the notebook PC 100 is furnished with functional components such as a CPU and memory, a recording medium drive such as a hard disk, and a video playing module and an audio playing module.
A problem with this sort of notebook PC 100 has been that in situations in which it is run on battery drive-such as at a trip destination where its AC adapter cannot be plugged in-the battery dies while watching a program, making listening and viewing impossible. Moreover, because power consumption in performing the decoding process in the signal-processing unit 130 varies drastically depending on the channel, owing to differing SDTV, HDTV, etc. image quality depending on the channel, predicting according to the remaining battery capacity how long listening and viewing is possible has been difficult.